Ioptcal Design Of LED Road Lamps With Nonsymmetrical Light Distribution

As the fourth generation light source, LED has a variety of excellent advantages, such asenvironment protection and energy saving. The world has entered a golden age of the LEDlighting. Especially in traditional road lighting usually high pressure sodium or metal halidelamps are utilized, which have big volume, not easy to control as well as light pollution andsome other shortcomings. These will cause zebra on the road, also cause bad effects on roadlighting. The LED has potential advantages such as control light color, small size, easy toinstall and second optical design, etc. It is significantly important to design a LED road lampwith good lighting effect.Base on realistic requirements of road lighting, in order to solve the glare and lightenergy waste, it designs a second optical system for LED source. It shows the optical designof LED road lamps with nonsymmetrical light distribution and the simulation results. Themajor results obtained are following:1. Summarize the development on the street lighting and progress of domestic andabroad. Investigates and analyzes the street lighting standards, characteristics of street lightingand the lighting goals to be obtained.2. Introduces the necessity of road lamp’s optical design, compared the characteristics ofsymmetrical and nonsymmetrical optical distribution. Basing on these a nonsymmetricaldesign was put forward, and according to the analysis by mathematic a suitable output light’sangle was selected.3. For the purpose of the uniformity of road surface, using the principle of energyconservation, a relationship between the output light’s angle and the necessary energy wasobtained from a suitable LED light source. Based on the mapping principle of the PolarCandela Distribution, a kind of secondary optical lens which used transmission optical designmethods had been designed.4. Using lighting design software TracePro, optical distribution curve of the designedLED lamp is obtained. The lens is realized to change the LED’s Lambertion distribution to thenonsymmetrical rectangular shape, and get a high uniformity of road surface illuminance. 5. By distributing the above design LEDs in a3×3matrix, a LED module is realized.Then combining the heat sinking construct, driving circuit, a LED road lamp product withnonsymmetrical optical design is obtained. Using DIALUX to analysis and compute thedistribution curve, the result is very good for the road lighting. Comparing with thesymmetrical light distribution, the results of the nonsymmetrical one is more suitable andbetter than the symmetrical one.